2000Z28M6

iTrader: (13)

I have searched around and read and read, and at this point my car is gettin up there in mileage so it makes it harder to pin down an exact culprit.

Seems my car is running shitty from 2k -3k rpm. I cant really recall when it started all i kno its been like this for bout 3months now.

OK example:

5pm get out of work its usually like 80-90 degrees outside.
start the car no problem.
take off no problem unless i go over 2k rpm.
get on to the freeway no matter what gear as soon as I get to 2k-3k rpm car just boggs and feels like its struggling.
the messed up part is that it usually gets a lil better once the engine warms up.

So it feels like a damn dog when I hit 2k -3k rpm. when engine Cold.

At this point Ive changed the fuel filter, spark plugs, wires, cleaned the air filter and put in one of those fuel injector cleaners.

Is it my cam? can a tune go out of wack?
Do i check my 02s?
No SES lights, do I get it scanned?
Check MAF?
clogged injectors?
dirty manifold?

it could be anything?
Help please.......

komik

iTrader: (7)

What you're describing is exactly what my TA did before I replaced the fuel pump. If the weather was cold and the car didn't run for too long, it was fine. But in warmer weather and / or after a long drive it would stall over 2K. But whenever I tried to have it checked somewhere, it would act normal. Finally I got it to a shop when it wasn't working. When they rode with me I had to floor it to go 5 mph. They checked the fuel pressure and found it to be way below operating range. I let it cool off for about 20 minutes, made it home, and left it there until I replaced the pump.

staringback05

iTrader: (8)

fuel pump....or......coil packs

2000Z28M6

iTrader: (13)

how much pressure should thier be up in the fuel rails? How do you check the coil packs?
Thanks

SSucese

iTrader: (1)

Around 60psi is what you should expect to find it you take a gauge and test it at the schrader valve. I myself thought I had a bad fuel pump being that mine was only getting 20psi up there however in the end my fuel pressure regulator went bad but still required just as much work trying to change it being that on LS1's its located in the tank.

hawk99354

I have what sounds to be like that same problem as 2000Z28M6. Although after take it to a local dealership they ruled out the fuel and ignition system saying the MAF or ECM was to blame. But from this thread it sounds like they were just throwing out guesses because they were out of idea's. If a fix is found I'd appreciate the info.

c0ncEpT

iTrader: (4)

My car use to run HORRIBLY when it was cold. Like anything over 2K and I think a stock civic could have handed me my ***. But the warmer it got the better it ran. I got some QD Contact Cleaner from Home Depot and cleaned my MAF and its not 100% better. I dont know if this is your problem but a can is only like $6 bucks so it wouldent hurt to try.

2000Z28M6

iTrader: (13)

Ok guys....i didnt get scanned sooner because my check engine light never comes on, but anyways I got it scanned today for codes. This is what came up:

P0135 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0155 - O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

P0160 - O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
P0140 - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

AND ALSO

P0122 - Throttle/Petal Position Sensor/Switch A Circuit Low Input

Make note my car has headers so it only operates with 2 O2 sensors not 4 like when stock.

Any input? Besides change the remaining 2 out with new ones? What about the TPS sensor code?

Thanx

ak77ta

iTrader: (2)

o2 sensor heater circuit codes area caused by the sensors themselves 9 times out of 10. Aftermarket remote starts have caused these codes in my experience-i dunno if you have one of these units or not. This could explain why the car runs better once it warms up-the heaters are not getting the o2 sensors to closed loop quickly like theyre supposed to but this could be caused by youre headers since theyre located further back from stock. The tps code i would definitely take a look at. If you have access to a scan tool make sure the tps % goes from 0-100 like it should, but i would suspect a faulty sensor but could be a wiring issue. This could definitely cause a dead spot in the rpm/tps range. Low fuel pressure would cause running badly off idle to redline and get worse on the way up the rpm range. Coil packs cause individual cylinder dead misfires. Hope this helps

staringback05

iTrader: (8)

replace the o2s, make sure the the wires havent been on the headers...you can also change out the TPS, the sensor goes out and there not that expensive...

2000Z28M6

iTrader: (13)

Ok i took it to get re scanned and i stil got the same codes. I thought I reset the PCM, I mean I d/c the ground and let it sit for bout 10mins? Did I reset it properly?

However I did get a P0300 which wasnt there last time?
P0300 Random/Multiple Cylinder Misfire Detected ?

Should I check something else?

mattraypharbor

iTrader: (2)

did you ever replace the tps? and did it work if you did?

2000Z28M6

iTrader: (13)

yea i swapped out the tps. And truthfully it seemed to help, but I still got the code again. Did I not reset the PCM correctly?

oneBADDz

iTrader: (26)

you need to clean your mass airflow sensor and make sure all the wires are plugged in on the intake piping. both front O2s don't start acting up at the same time generally, and when you get both codes at once it's probably the MAF. If not, you may have just gotten a bad tank of gas.